The invention pertains to a method of assembling a stator for an electric machine of the type utilizing a bell-shaped rotor, which is freely rotatable in a cylindrical air gap provided between a permanent magnet and a cylindrical flux return part surrounding the permanent magnet in an equidistant relationship.
In assembling machines of the general construction described above, the permanent magnet is filled with plastics material and is glued to a face plate. The assembly is then bored to provide a bearing seat and is secured to a flux return element, for example by a press-fit. The manufacture of such an electric machine is expensive and presents serious problems in achieving close tolerances.
It is further known to interconnect the permanent magnet and the flux return element by a face plate made of a plastics material. Such a design requires close tolerances of the permanent magnet as well as of the flux return element and is likewise costly in manufacture.
In another known construction, the permanent magnet and a face plate made of aluminum are secured by injecting a curable plastics material.
In another, widespread known stator, the flux return ring is press-fitted into a housing in a distance from the face plate. Such a construction, however, necessitates machining the outer surface of the flux return ring as well as the inner surface of the housing to close tolerances and therefore is rather costly.
It is an object of the invention to provide a method for assembling a stator for an electric machine of the aforementioned kind, which method is easy to perform and requires machining to high tolerances of but a few components of the stator.
It is another object of the invention to provide such a method for assembling, which does not necessitate machining the flux return ring to high tolerances.